1. Field of the Invention
The present invention relates to an automotive impact absorbing member for absorbing impact force and protecting passengers in the event of a car crash.
2. Description of the Related Art
Automotive impact absorbing members which are capable of absorbing a jarring load in the event of a car crash have been employed for some time in automobile bumpers or the members which form the cabin, for example. Once such type of impact absorbing member has a structure furnished with a plate-shaped rib portion that extends in the direction perpendicular to the direction of input of impact load; and load transmitting portions connecting with the rib portion at either widthwise end thereof for transmitting the widthwise direction component force component of the impact load to the rib portion. Such designs are taught, for example, in Patent Document 1 (JP-A-06-171441) and Patent Document 2 (JP-A-2006-062635), and are constituted in such a way that the impact load will be input to the load transmitting portions, giving rise to tensile deformation of the rib portion in its widthwise direction, with the energy of impact being absorbed on the basis of energy loss resulting inter alia from ductility of the rib portion.
In the impact absorbing members of the conventional designs taught in the aforementioned Patent Documents 1 and 2, it has proven difficult to produce a rib portion of uniform thickness owing to variability in the precision of the molding process and other such production-related issues, and there exists a need for more advanced technology to achieve uniform thickness.
For this reason, it has proven difficult to predict the locations in the rib portion at which will form thin sections where localized strain (necking) is likely to occur in association with tensile stress due to the small cross sectional area. Particularly where such thin sections are produced at the ends of the rib portion, there is a risk that a problem such as the following will occur.